. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 648 NERVOUS SYSTEM. (NERVOUS CENTRES. GREY NERVOUS MATTEK.) It is in vain, in the present state of our knowledge, to speculate upon the use of these caudate processes. Do they constitute a bond of union between the nerve-vesicles and certain nerve-tubes? or are they comraissural fibres serving to connect the grey substance of different portions of the nervous centres ? Until a more extended research has made us better acquainted with the peculiarities of these vesicles in various localities, it would be premature to offe
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 648 NERVOUS SYSTEM. (NERVOUS CENTRES. GREY NERVOUS MATTEK.) It is in vain, in the present state of our knowledge, to speculate upon the use of these caudate processes. Do they constitute a bond of union between the nerve-vesicles and certain nerve-tubes? or are they comraissural fibres serving to connect the grey substance of different portions of the nervous centres ? Until a more extended research has made us better acquainted with the peculiarities of these vesicles in various localities, it would be premature to offer any conjecture concerning their precise relation to the other elements of the nervous centres. They exist, with different degrees of developement, in the locus niger of the crus cerebri, in the laminae of the cerebellum, in the grey matter of the spinal cord and medulla oblongata, and in the ganglions, and in the grey substance of the cerebral convolutions, in which latter situa- tion they are generally of small size. When a portion of grey matter from a con- volution of the brain is examined with a high power in the microscope, we observe it to con- sist chiefly of a mass of granular matter, in which nerve-vesicles are imbedded with consi- derable intervals between them. Henle states, with much truth, that the superficial part of the grey matter of the convolutions seems almost entirely composed of finely granular substance, in which lie, scattered here and there, several clear vesicles which, as he remarks, look almost like openings (fig. 372). In the middle por- tion the vesicles appear larger, and the gra- nular matter becomes less abundant, and on the most deep-seated plane the nerve-vesicles are much increased in size and lie in closer juxtaposition, being, however, covered by a thin layer of granular matter, which forms a sheath to each vesicle. Nerve-tubes are found throughout the whole depth of the grey matter. Those in the most superficial layer are ex- tremely fin
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